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<title>Apply a user function recursively to every member of an array</title>
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<h1 class="refname">array_walk_recursive</h1>
<p class="verinfo">(PHP 5)</p><p class="refpurpose"><span class="refname">array_walk_recursive</span> — <span class="dc-title">Apply a user function recursively to every member of an array</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.array-walk-recursive-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>array_walk_recursive</strong></span>
( <span class="methodparam"><span class="type">array</span> <code class="parameter reference">&$array</code></span>
, <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>
[, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$userdata</code><span class="initializer"> = <strong><code>NULL</code></strong></span></span>
] )</div>
<p class="para rdfs-comment">
Applies the user-defined <em><code class="parameter">callback</code></em> function to each
element of the <em><code class="parameter">array</code></em>. This function will recurse
into deeper arrays.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.array-walk-recursive-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">array</code></em></span>
<dd>
<p class="para">
The input array.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">callback</code></em></span>
<dd>
<p class="para">
Typically, <em><code class="parameter">callback</code></em> takes on two parameters.
The <em><code class="parameter">array</code></em> parameter's value being the first, and
the key/index second.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
If <em><code class="parameter">callback</code></em> needs to be working with the
actual values of the array, specify the first parameter of
<em><code class="parameter">callback</code></em> as a
<a href="language.references.html" class="link">reference</a>. Then,
any changes made to those elements will be made in the
original array itself.
</p>
</p></blockquote>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">userdata</code></em></span>
<dd>
<p class="para">
If the optional <em><code class="parameter">userdata</code></em> parameter is supplied,
it will be passed as the third parameter to the
<em><code class="parameter">callback</code></em>.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.array-walk-recursive-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> on success or <strong><code>FALSE</code></strong> on failure.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.array-walk-recursive-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-4997">
<p><strong>Example #1 <span class="function"><strong>array_walk_recursive()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$sweet </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'a' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'apple'</span><span style="color: #007700">, </span><span style="color: #DD0000">'b' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'banana'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$fruits </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'sweet' </span><span style="color: #007700">=> </span><span style="color: #0000BB">$sweet</span><span style="color: #007700">, </span><span style="color: #DD0000">'sour' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'lemon'</span><span style="color: #007700">);<br /><br />function </span><span style="color: #0000BB">test_print</span><span style="color: #007700">(</span><span style="color: #0000BB">$item</span><span style="color: #007700">, </span><span style="color: #0000BB">$key</span><span style="color: #007700">)<br />{<br /> echo </span><span style="color: #DD0000">"</span><span style="color: #0000BB">$key</span><span style="color: #DD0000"> holds </span><span style="color: #0000BB">$item</span><span style="color: #DD0000">\n"</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">array_walk_recursive</span><span style="color: #007700">(</span><span style="color: #0000BB">$fruits</span><span style="color: #007700">, </span><span style="color: #DD0000">'test_print'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
a holds apple
b holds banana
sour holds lemon
</pre></div>
</div>
<div class="example-contents"><p>
You may notice that the key '<em>sweet</em>' is never displayed. Any key that holds an
<span class="type"><a href="language.types.array.html" class="type array">array</a></span> will not be passed to the function.
</p></div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.array-walk-recursive-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.array-walk.html" class="function" rel="rdfs-seeAlso">array_walk()</a> - Apply a user function to every member of an array</span></li>
<li class="member">information about the <a href="language.pseudo-types.html#language.types.callback" class="link">callback</a> type</li>
</ul>
</p>
</div>
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